The focus of the laboratory is on mechanisms of drug resistance. Two systems are being studied in depth: mechanisms of multidrug resistance and mechanisms of cisplatin resistance. Our aim is to identify the various mechanisms involved in these two systems, by utilizing drug resistant cell lines and various molecular approaches. The availability of probes which can recognize amplified/overexpressed sequences in drug resistant cell lines will offer a starting point for identification of the mechanism involved as well as help in devising approaches to overcome this. In addition, it will provide useful tools to probe primary and recurrent tumor samples to aid in the understanding of the mechanisms of primary and acquired drug resistance in human tumors.